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EN31 is a high carbon Alloy steel which achieves a high degree of hardness with compressive strength and abrasion resistance.

Forge at 1000°/1050°C. Heat slowly, allowing sufficient time at the forging temperature for the steel to be thoroughly soaked through. Re-heat as often as necessary to keep the temperature above 850°C. After forging cool very slowly, preferably in a furnace.

Heat uniformly to 800°C, equalize, then furnace cool. (Hardness about 229 Brinell).

If machining operations have been heavy or if the tool has an unbalanced section, remove stresses before hardening by heating up to 700°C, equalize, then cool slowly.

Heat uniformly to 800/820°C until heated through. Allow 30 minutes per inch of ruling section and quench immediately in oil.

Heat uniformly and thoroughly at the selected tempering temperatures and hold for at least one hour per inch of total thickness

Cold-work tool steels which include D2, D3, D4, D5, and D7 steels are high-carbon, high-chromium steels. Apart from D3 steel all group D steels have 1% Mo and are air hardened. Type D3 steel is oil-quenched; though small sections can be gas quenched after austenitization using vacuum. As a result, tools made with type D3 steel tend to be brittle during hardening. Type D2 steel is the most commonly used steel among the group D steels. The D3 steels contain 1.5 to 2.35% of carbon and 12% of chromium.

The following table shows the thermal properties of D3 steels.

The mechanical properties of D3 steels are tabulated below:

Equivalent metals of D3 steel are:

Annealing of D3 tool steel needs to be done in a controlled atmosphere furnace. D3 tool steels should be heated thoroughly to 871°C (1600°F) and cooled slowly at a rate of not more than -6°C (20°F) per hour, until the furnace is black. Then the material should be removed and air cooled.

D3 tool steel requires hardening and tempering to achieve maximum properties. For maximum accuracy, the parts of D3 tool steel should be stress relieved after roughing operations. Stress should be relieved at 648°C (1200°F) for one hour and cooled slowly.

After rough machining the tool should be heated through to 650°C (1200°F), holding time 2 hours. Cool slowly to 500°C (930°F), then freely in air.HARDENING

D3 tool steel should be heated properly since it is very sensitive to overheating and if not heated maximum hardness cannot be achieved. The work should be directly placed in a furnace preheated to 954°C (1750°F) and soaked for 20-25 minutes, plus 5 minutes per inch of thickness, and then oil-quenched to harden it.

The D3 tool steel should be cooled to room temperature and should be tempered immediately. The parts should be placed in the tempering furnace and increased slowly to the desired tempering temperature. Tempering for 1 hour per inch of thickness is required.

Cold work tool steels are employed for the manufacture of tools for applications involving surface temperatures below 200°C.
In this temperature range, the steel must feature the following properties in order to guarantee tool resistance to the high stresses arising from the numerous machining and shaping procedures:

Micro-Melt® 420-CW tool steel is a corrosion-resistant, high vanadium wear-resistant tool steel produced using Carpenter’s Micro-Melt powder process. The wear resistance of this grade is comparable to Micro-Melt A11-LVC alloy. Micro-Melt 420-CW alloy also is comparable in toughness to Micro-Melt A11 alloy. Micro-Melt 420-CW may be considered for those applications where 440C and D2 tool steels do not have adequate wear resistance or for applications where A11-LVC, A11, D2 or other tool steels do not have adequate corrosion resistance.
Many of the benefits realized in the use of Micro-Melt powder metals, such as Micro-Melt 420-CW alloy, are a direct result of the refined microstructure (small, uniformly distributed carbide particles and a fine grain size) and the lack of segregation in the powder metallurgy product. These advantages include ease of grinding, improved response to heat treatment, greater wear resistance, and increased toughness of the finished tool.

Micro-Melt 420-CW alloy may be considered for:

• Plastic injection molds and inserts
• Plastic injection and extrusion feedscrews
• Non-return valve components
• Pelletizing equipment
• Pelletizer blades
• Nozzles
• Gate and nozzle inserts
• Industrial knives, slitters, and cutters
• Wear-resistant specialty cutlery
• Wear components for food and chemical processing
• Bearings, bushings, valves, rolls
• Gear pumps

Micro-Melt 420-CW tool steel, like all high carbon tool steels, is somewhat susceptible to decarburization in hardening. Means of preventing decarburization are well known. Modern furnaces that employ protective environments, such as protective atmospheres, salt pots, fluidized bed furnaces and vacuum furnaces, should present no difficulty with decarburization of this alloy.

Normalizing is not recommended.

D2 steel is an air hardening, high-carbon, high-chromium tool steel. It has high wear and abrasion resistant properties. It is heat treatable and will offer a hardness in the range 55-62 HRC, and is machinable in the annealed condition. D2 steel shows little distortion on correct hardening. D2 steel’s high chromium content gives it mild corrosion resisting properties in the hardened condition.Cold-work tool steels include the high-carbon, high-chromium steels or group D steels. These steels are designated as group D steels and consist of D2, D3, D4, D5, and D7 steels. These steels contain 1.5 to 2.35% of carbon and 12% of chromium. Except type D3 steel, all the other group D steels include 1% Mo and are air hardened. Type D3 steel is oil-quenched; though small sections can be gas quenched after austenitization using vacuum. As a result, tools made with type D3 steel tends to be brittle during hardening. Type D2 steel is the most commonly used steel among the group D steels.

Equivalent materials to D2 tool steels are:

• DIN 1.2379
• NI KU
• B.S. BD 2
• ASTM A681
• FED QQ-T-570
• SAE J437
• SAE J438
• UNS T30402

D2 steels should be preheated very slowly to 815ºC (1500ºF) and then temperature can be increased to 1010ºC (1850ºF). They are then held at 1010ºC (1850ºF) for 20 to 45 minutes and air cooled (air quenched).

Forging of D2 steels can be done from 1065ºC (1950ºF) down to 954ºC (1750ºF). Do not forge below 926ºC (1700ºF).

Soaking time = time at austenitlzIng temperature after the tool is fully heated through.

D2 is supplied in the annealed and machineable condition. Re-annealing will only be necessary if the steel has been forged or hardened by the toolmaker. To anneal, heat slowly and uniformly to 900°C. Soak for three to four hours and allow to cool in the furnace to room temperature. Re-heat to 800-1040°C and again soak for three to four hours. Allow to cool in the furnace to room temperature.

D2 steels can be tempered at 204ºC (400ºF) for achieving Rockwell C hardness of 61 and at 537ºC (1000ºF) for a Rockwell C hardness of 54.

Moulds for chemically aggressing Plastics & Plastics containing abrasive Filters.

This steel is easy turning, and should be made sharp knife, scissors, saw, cold or hot for repair mode, the drum side, the screw pattern, line mode, cutters, impact mode, circular cylinder, the system of power transformers heart dies, cutting steel Paper mill knives, steel forming rollers, special molding roller, precision rules, shape complexity of the cold tools, mandrels, metallurgy, tin for mold, plastic mold, the screw head molds.
SKD11 Tool Steel of Applications:

Protect the steel and heat through to 1560°F (850°C). Then cool in the furnace at 20°F (10°C) per hour to 1200°F (650°C), then freely in air.

After rough machining the tool should be heated through to 1200°F (650°C), holding time 2 hours. Cool slowly to 930°F (500°C), then freely in air.

Thread rolling dies, Hobs, Cold extrusion tools and dies, Punches, Draw plates and dies, Cutters, Measuring tools, Pressure casting moulds, Blanking, Reamer, Finishing rolls for tyre mills.
This type of steel has high dimensional stability with added wear resistance coupled with excellent edge holding qualities.
Cold-work tool steels include the high-carbon, high-chromium steels or group D steels. These steels are designated as group D steels and consist of D2, D3, D4, D5, and D7 steels. These steels contain 1.5 to 2.35% of carbon and 12% of chromium. Except type D3 steel, all the other group D steels include 1% Mo and are air hardened. Type D3 steel is oil-quenched; though small sections can be gas quenched after austenitization using vacuum. This makes tools made with type D3 steel brittle during hardening. Type D2 steel is the most commonly used steel among the group D steels.

The other designations of D5 tool steels are:

Applications of D5 steels include thread rolling, blanking or forming dies operating at temperatures below 482°C (900°F).

D5 steels should be preheated very slowly up to 815°C (1500°F), then temperature should be increased to 1009°C (1850°F) and held for 20 to 45 minutes. Then they are air quenched.

Forging of D5 steels can be done at 1065°C (1950°F) down to 1750°F. Do not forge below 926°C (1700°F).

Annealing of D5 steels should be done at 886°C (1627°F) followed by slow furnace cooling at 4°C (40°F) per hour or less.

D5 steels can be tempered at 204°C (400°F) for achieving Rockwell C hardness of 61 and at 537°C (1000°F) for a Rockwell C hardness of 54.

The following table shows the physical properties of P20 tool steels.

Toughness of a material determines whether it can be subjected to shock conditions, and the extent to which it may undergo deformity in shape but still not snap. If subjected to a proper treatment process, O1 Tool Steel tends to be very tough. As opposed to toughness, brittleness measures whether a material will snap instead of getting deformed, when load is applied. Alloy steels like O1 Tool Steel are less brittle than cast or pig iron because of the presence of magnesium.

Chromium hot-work tool steels are designated as group H steels according to the AISI classification system. This series of steels start from H1 to H19. The most commonly used chromium hot-work steels are H11, H12, and H13, which can be air hardened in 150 mm thick sections. The steels are subjected to minimal distortion during hardening due to their balanced alloy content. The tools produced from chromium hot-work steels can be cooled using water without damage as these steels have low carbon and alloy contents.
This article will give an overview of H13 chromium hot-work steels, which contain strengthening agents such as vanadium and molybdenum. These steels are resistant to softening at elevated temperatures due to the presence of chromium content.

The following table shows the thermal properties of H13 tool steels.

The physical properties of H13 tool steels are given in the following table

The mechanical properties of H13 tool steels are tabulated below.

Other designations that are equivalent to H13 tool steels include:

The machinability rate of H13 tool steels is nearly 75% of that of the W group tool steels.

H13 tool steels are formed by using conventional methods.

H13 tool steels are readily weldable.

H13 tool steels are preheated to 816°C (1500°F). Then the steels are directly heated by increasing the temperature to 1010°C (1850°F) followed by holding for 15 to 40 mins. The steels are then air-quenched.

H13 tool steels are forged at 1079°C (1975°F). For this type of steels, forging below 898°C (1650°F) is not preferable.

Cold working may be carried out on H13 tool steels using conventional methods.

H13 tool steels are annealed at 871°C (1600°F) and slowly cooled at 4°C (40°F) in the furnace.

H-11 HOT WORK TOOL STEEL
Chromium hot-work tool steels are designated as group H steels according to the AISI classification system. This series of steels start from H1 to H19. The most commonly used chromium hot-work steels are H11, H12, and H13, which can be air hardened in 150 mm thick sections. The steels are subjected to minimal distortion during hardening due to their balanced alloy content. The tools produced from chromium hot-work steels can be cooled using water without damage as these steels have low carbon and alloy contents.
This article will give an overview of H11 chromium hot-work steels, which have low carbon content and good toughness. These steels can be deep hardened by heat treatment and air-quenching.
Chemical composition ElementMinMaxCarbon, C0.320.42Manganese, Mn1.100.50Silicon, Si0.801.20Molybdenum, Mo1.001.50Chromium,Cr4.505.50W----Vanadium, V0.801.20Co---- Thermal Properties
The following table shows the thermal properties of H11 tool steels.
Thermal propertiesMetricImperialThermal expansion (@20-100ºC/68-212ºF)11.9 x 10-6/ºC6.63 µin/in°FThermal conductivity (@100ºC/212ºF)42.2 W/mK292.9 in/hr.ft².°F Physical Properties
The physical properties of H11 tool steels are given in the following table.
Physical propertiesMetricImperialDensity7.81 g/cm30.282 lb/in3Melting point1427°C2600°F Mechanical Properties
The mechanical properties of H11 tool steels are tabulated below.
PropertiesMetricImperialHardness, Rockwell C (air cooled from 982°C, 45 mins)52.552.5Hardness, Rockwell C (air cooled from 1010°C, 45 mins)5656Hardness, Rockwell C (air cooled from 1038°C, 45 mins)5757Modulus of elasticity207 GPa30000 ksiModulus of elasticity (@538°C/1000°F)159 GPa23000 ksiModulus of elasticity (@204°C/400°F)190 GPa27500 ksiCharpy impact (V-notch; air cooled from 1010°C;535°C temper temperature)13.6 J10.0 ft-lbCharpy impact (V-notch; air cooled from 1010°C;650°C temper temperature)27.1 J20.0 ft-lbCharpy impact (V-notch; air cooled from 1010°C;370°C temper temperature)33.9 J25.0 ft-lbMachinability (1% carbon steel)75.0 - 80.0%75.0 - 80.0%Poisson''s ratio0.27-0.300.27-0.30 Other Designations
Other designations that are equivalent to H11 tool steels include:
• AFNOR Z 38 CDV 5
• DIN 1.2343
• UNI KU
• JIS SKD6
• B.S. BH 11
• AMS 6437
• AMS 6485
• AMS 6487
• AMS 6488
• ASTM A681
• FED QQ-T-570
• SAE J437
• SAE J438
• SAE J467
• UNS T20811
• AISI 610
• ASTM A579
• MIL S-47262Machinability
The machinability rate of H11 tool steels is nearly 75% of that of the W group tool steels.
Forming
H11 tool steels are formed by using conventional methods, machining and forging.